The acquisition of ViroPharma Inc. (NASDAQ:VPHM) would add up to three new compounds to the rare disease pipeline of Shire plc (LSE:SHP; NASDAQ:SHPG). Not counting line extensions of marketed drugs, the combined company would have a total of seven rare disease programs in the clinic, if ViroPharma's option to an oral budesonide suspension is exercised. That program, from Meritage Pharma Inc., is